People with occupations that require long periods of sitting and people who use wheelchairs are often affected by low back pain, poor blood circulation of the lower body, and pressure sores. Low back pain associated with extended sitting is likely caused by poor sitting posture which flattens the natural curvature of the spine and increases the stress on back muscles. Sitting related pressure sores are primarily caused by concentrated pressure on a posterior area of a hip bone, for example, ischial tuberosities or coccyx, of a person who sits extensively. This concentration of pressure can cause ischial or coccyx pressure sores over time. Adjustment of the seating position of the user to redistribute contact pressure of the user promotes an increase in blood circulation, a reduction in risk of pressure sores, and a promoted healing process of established pressure sores.
Users are advised that during extended sitting they should occasionally perform “push-ups” in their chair to adjust their seating position and reduce contact pressure that may otherwise cause pressure sores. Users of wheelchairs may have a disability or lack strength that prevents them from performing the push-up or adjusting their seating position themselves. They may also be unable to notice when poor circulation and sustained elevated pressures give rise to pressure sores.
Thus, a need exists for a seat and backrest that promote an increase in circulation. A further need exists for the seat and backrest to promote a reduction in contact pressure build-up for a user. A still further need exists for the seat and backrest to promote a restoration of the natural curvature of the spine for the user. Another need exists for the seat and backrest to promote a reduction in stress of the back muscles of the user. Yet another need exists for the seat and backrest to promote comfort for the user over extended periods of sitting.